The Gemara (Succah 26a) states: “People who travel by day are exempt from succah during the day but are obligated at night. People who travel by night are exempt from succah at night but are obligated during the day. People who travel both during the day and at night are exempt from succah both during the day and at night.”

Why are travelers exempt from the requirement of succah? Rashi explains that the Torah states “You shall live in succos for seven days” and Chazal interpret this as “teishvu k’ein taduru” i.e. a person should live in the succah in the same manner in which he lives in his home. Thus just as a person does not refrain from leaving his home during the year to take a business trip the Torah does not require a person to refrain from taking a trip during Succos either even though it will mean that he will not be able to live in his succah.

Indeed the Shulchan Aruch (Orach Chayim 640:8) rules in accordance with the Gemara’s statement: “People who travel by day are exempt from succah during the day and are obligated at night. People who travel at night are exempt at night and obligated during the day.”

Daytime Travels Nighttime Succah

Is a person who travels during the day obligated to build a succah at night if an existing one isn’t readily available? This question is the subject of a dispute between early halachic authorities (cited in Biur Halachah sec. 640; Chayei Adam klal 147 sec. 22; and Shu”t Yechaveh Daas by Rav Ovadiah Yosef shlita vol. 3 sec. 47). While the Gemara indicates that people who are traveling only during the day are obligated to observe the mitzvah of succah at night Levush maintains that this is true only in the event that a succah is already available in the place where they are staying over. If there is no succah there however Chazal did not require travelers to go to the trouble of erecting one in which to sleep for the night. Magen Avraham however disagrees with Levush and rules that daytime travelers must even fabricate a succah at night if a ready-made one is not available. 

Chayei Adam rules in accordance with Levush reasoning that requiring a traveler to build a succah would entail hours of strenuous labor an imposition that certainly does not fit the criterion of “teishvu k’ein taduru.” Chayei Adam finds support for this ruling  in the commentary of Meiri (Succah 26a) who  writes that a traveler is not obligated to build a succah at night although if he finds himself in a place where there is a succah he is not permitted to eat or sleep outside it. Rav Ovadiah Yosef rules that the halachah follows the opinion of Levush and Chayei Adam.